The residual stress-induced buckling of annular thin plates and its application in residual stress measurement of thin films

The buckling method is presently one of the most commonly used methods in residual stress measurement, but still suffers from the problem that an array of structures occupying a large die area is required. In this paper, the buckling characteristics of annular thin plates were investigated and a new buckling method based on annular thin plates was proposed, implemented and verified for in situ measurement of both compressive and tensile stress with only a single structure but not an array. Annular thin plates with variable inner radius were realized by the sacrificial oxide etching of circular thin plates. The critical inner radius was measured by an optical microscope and was used to predict the residual stress by eigenvalue buckling analysis of ANSYS software. To measure both tensile and compressive stress with the same structure was proved to be feasible. Further measurements of compressive stress in thin polysilicon films have been carried out by this method and have shown reasonable agreement with results by micro-rotating gauge method. (c) 2007 Elsevier B.V. All rights reserved.